Topic 4747 failed to build, and the following output was written:

<?xml version="1.0" encoding="UTF-8"?>
<section>
    <title>Injection Error</title>
    <warning>
	<title>Topic 4747 failed Injection processing.</title>
        <para>Topic 4747 failed Injection processing and is not included in
this build.</para>
        <para>Please review the compiler error for <xref linkend="TagErrorXRef4747"/> for more detailed information.</para>
    </warning>
</section>


Elsewhere in the build another topic referenced this topic, so Publican complained: 

Validation failed: 
topics/4746.xml:15: validity error : IDREF attribute linkend references an unknown ID "TopicID4747"
 

The injector should write the section id attribute so that it doesn't break linking.

This might need fixing upstream in the Skynet injection code. Triage and reassign to the web-Topic_Index component for Matt if that's the case.